In Australia, there were national issues on the use of potassium ampoules (resulting in patient deaths), which led to the removal of the ampoules from clinical areas. A decision was made by the Medication Safety Committee at a metropolitan Melbourne hospital to remove potassium ampoules from ward areas as part of the establishment of a hospital-wide potassium guideline. As a result, the nurses in the cardiothoracic ward Practice Review Committee identified the need to review the proposed practice of treating hypokalaemia with 30 mmol of potassium chloride (KCL) in 1000 mL over an extended period in postoperative cardiothoracic patients. The challenge was to develop a practice to safely administer intravenous KCL in fluid restricted patients in addition to the hospital guidelines to prevent hypokalaemic-induced cardiac dysrhythmias. A literature search revealed there were no clear or uniform approaches to guide our practice in addressing this clinical problem. The Practice Review Committee developed a KCL administration guideline based on a review of the available literature. The Practice Review Committee developed a ward-based guideline that addressed infusion concentration, duration of administration, responsiveness of nurses to severity of hypokalaemia and the evaluation of treatment by measuring serum potassium after replacement. This ward-based guideline was based on benchmarking from similar institutions and relevant literature. The review process provided an opportunity for the staff to critique their practice to improve patient care and allowed regular evaluation of the implemented practice guideline. The ward-based guideline required a revision as patients' renal function was not being taken into consideration prior to potassium infusions being administered. The implementation of the ward-based guideline into practice has been well received by the staff as it has allowed consistent practice and timely treatment of hypokalaemia.